Gabriel Landini

S100 and Cytokine Expression in Caries

ABSTRACT The molecular immune response of the pulpal tissue during chronic carious infection is poorly characterized. Our objective was to examine the expression of potential molecular mediators of pulpal inflammation, correlate their levels with disease severity, and determine the cellular localization of key molecules. Results indicated that there was significantly increased transcriptional activity in carious compared to healthy pulp, and the increase correlated positively with disease severity. Semiquantitative reverse transcriptase PCR analysis in 10 carious and 10 healthy pulpal tissue samples of the S100 family members S100A8, S100A9, S100A10, S100A12, and S100A13; the cytokines tumor necrosis factor alpha (TNF-α), interleukin-1β (IL-1β), IL-8, IL-6, and epithelial cell-derived neutrophil attractant 78 (ENA-78); and the structural protein collagen-1α indicated that all genes tested, with the exception of S100A10, were more abundantly expressed in carious teeth. In addition, we found that the closer the carious lesion front was to the pulpal chamber the higher the expression was for all genes except S100A10. Multiple-regression analysis identified a significant positive correlation between the expression levels of S100A8 and IL-1β, ENA-78, and IL-6 and between collagen-1α and S100A8, TNF-α, IL-1β, IL-8, IL-6, and ENA-78. Immunohistochemical studies in carious pulpal tissue indicated that S100A8 and the S100A8/S100A9 complex were predominantly expressed by infiltrating neutrophils. Gene expression analyses in immune system cells supported these findings and indicated that bacterial activation of neutrophils caused upregulation of S100A8, S100A9, and S100A13. This study highlights the complex nature of the molecular immune response that occurs during carious infection.

Fractal analysis of the normal human retinal fluorescein angiogram

The fractal dimension of the retinal vasculature and isolated venous and arterial trees down to a caliber of 40 microns was estimated in 23 routine fluorescein angiograms of normal retinas. Fractal dimension was determined with a method based on the box counting theorem. This method is less susceptible to the radial architecture of the retinal vascular tree than those previously reported (mass-radius relation and density-density correlation function). Two scale ranges with different fractal dimension were consistently present. The estimated fractal dimensions showed no significant difference between isolated arterial and venous trees which is not supported by previous reports. This method was designed for simple application in a clinical setting.

The Origin of Phenotypic Heterogeneity in a Clonal Cell Population In Vitro

Background The spontaneous emergence of phenotypic heterogeneity in clonal populations of mammalian cells in vitro is a rule rather than an exception. We consider two simple, mutually non-exclusive models that explain the generation of diverse cell types in a homogeneous population. In the first model, the phenotypic switch is the consequence of extrinsic factors. Initially identical cells may become different because they encounter different local environments that induce adaptive responses. According to the second model, the phenotypic switch is intrinsic to the cells that may occur even in homogeneous environments. Principal Findings We have investigated the “extrinsic” and the “intrinsic” mechanisms using computer simulations and experimentation. First, we simulated in silico the emergence of two cell types in a clonal cell population using a multiagent model. Both mechanisms produced stable phenotypic heterogeneity, but the distribution of the cell types was different. The “intrinsic” model predicted an even distribution of the rare phenotype cells, while in the “extrinsic” model these cells formed small clusters. The key predictions of the two models were confronted with the results obtained experimentally using a myogenic cell line. Conclusions The observations emphasize the importance of the “ecological” context and suggest that, consistently with the “extrinsic” model, local stochastic interactions between phenotypically identical cells play a key role in the initiation of phenotypic switch. Nevertheless, the “intrinsic” model also shows some other aspects of reality: The phenotypic switch is not triggered exclusively by the local environmental variations, but also depends to some extent on the phenotypic intrinsic robustness of the cells.

Fractals in microscopy

Fractal geometry, developed by B. Mandelbrot, has provided new key concepts necessary to the understanding and quantification of some aspects of pattern and shape randomness, irregularity, complexity and self‐similarity. In the field of microscopy, fractals have profound implications in relation to the effects of magnification and scaling on morphology and to the methodological approaches necessary to measure self‐similar structures. In this article are reviewed the fundamental concepts on which fractal geometry is based, their relevance to the microscopy field as well as a number of technical details that can help improving the robustness of morphological analyses when applied to microscopy problems.

Quantification of the Global and Local Complexity of the Epithelial-Connective Tissue Interface of Normal, Dysplastic, and Neoplastic Oral Mucosae Using Digital Imaging

This study aimed at quantifying the complexity of the epithelial-connective tissue interface (ECTI) in human normal mucosa, premalignant, and malignant lesions using fractal geometry. Two approaches were used to describe the complexity of 377 oral mucosa ECTI profiles. The box counting method was used to estimate their global fractal dimension, while local fractal dimensions were estimated using the mass radius relation at various local scales. The ECTI complexity significantly increased from normal through premalignant to malignant profiles in both global and local (over 283 microm) scales. Normal mucosa samples from different sites of the oral cavity also had different degrees of global complexity. Fractal geometry is a useful morphological marker of tissue complexity changes taking place during epithelial malignancy and premalignancy, and we propose it as a quantitative marker of epithelial complexity.

Estimation of tissue layer level by sequential morphological reconstruction.

An automated method for labelling layers of clustered elements in two dimensional images based on morphological operations is presented here. Unlike the various distance transforms for regular lattices, the procedure deals successfully with clusters composed of different shaped and sized elements and provides a distance measure, in number of layers, from each element in the cluster to any other reference element (or elements). The method was applied to histological sections of two different types of polystratified epithelia. Local clusters in the different cell profile layers can subsequently be used to define the orientation of the tissue layers relative to each element in it.

Vibration characteristics of ultrasonic scalers assessed with scanning laser vibrometry

OBJECTIVES Scanning laser vibrometry is a non-invasive method of accurately measuring the vibratory characteristics of oscillating objects. The aim of this study was to observe, using a scanning laser vibrometer (SLV), the vibration patterns of dental ultrasonic scaler tips and to assess the effects of water flow rate and power setting on these patterns whilst operating the tips in an unloaded environment. METHODS A 30kHz ultrasonic scaler (TFI-10, Dentsply) was fixed in position and a laser beam from the SLV was focused onto the tip. The laser, guided by a virtual measurement grid, was scanned over the oscillating tip surface. Scans were taken with the laser beam perpendicular to the long axis of the front face of the tip. RESULTS Oscillation frequencies and the displacement amplitude at the unconstrained end of the tip were measured for various power/water settings. Vibration nodal positions were recorded for the various settings and were found to occur approximately 4mm from the free end of the tip. At low and medium power settings, tip displacement amplitude was reduced by increased water flow. At high power settings, combined with a high flow rate, the water leaves the body of the instrument as a jet. This left the tip relatively unconstrained, allowing it to oscillate at increased displacement amplitudes. CONCLUSIONS This study shows that the SLV is able to accurately characterise the movement of oscillating ultrasonic scaler tips. The tips are affected by power setting and water flow rates.

Morphometrical differences between pseudo-epitheliomatous hyperplasia in granular cell tumours and squamous cell carcinomas

Aim : Granular cell tumour (GCT) is a benign tumour which occasionally induces pseudo‐epitheliomatous hyperplasia (PEH) of the covering epithelium, mimicking squamous cell carcinoma (SCC) invasion. PEH cells do not show marked atypia, but the presence of pseudoinvasive patterns remains a diagnostic problem since several misdiagnosed cases have been reported. This study investigated objective morphometric criteria to distinguish GCT‐PEH from SCC.

Ultrasonic Scaler Oscillations and Tooth-surface Defects

Damage to tooth root surfaces may occur during ultrasonic cleaning with both piezoelectric and magnetostrictive ultrasonic scalers. It is unclear which mechanism causes more damage or how their mechanism of action leads to such damage. Our null hypothesis is that tooth-surface defect dimensions, resulting from instrumentation with ultrasonic scalers, are independent of whether the scaler probe is magnetostrictive or piezoelectric. Piezoelectric and magnetostrictive ultrasonic scaler probes were placed into contact against polished dentin samples (100 g/200 g). Resulting tooth surfaces were evaluated with a laser metrology system. Ultrasonic instrumentation produced an indentation directly related to the bodily movement of the probe as it made an impact on the surface. Load, generator power, and probe cross-section significantly affected probe vibration and defect depth/volume. Defect dimensions were independent of generator type. Magnetostrictive probes oscillated with greater displacement amplitudes than piezoelectric probes, but produced similar defects. This may be due to the cross-sectional shape of the probes.

A new insight into the oscillation characteristics of endosonic files used in dentistry

The aim of this study was to assess the oscillation characteristics of unconstrained endosonic files using a scanning laser vibrometer (SLV). Factors investigated included file vibration frequency and node/antinode location as well as the variation in file displacement amplitude due to increasing generator power setting. A 30 kHz Mini Piezon generator (Electro-Medical Systems, Switzerland) was used in conjunction with a #15 and #35 K-file. Each file was fixed in position with the long axis of the file perpendicular to the SLV camera head. The laser from the SLV was scanned over the length of the oscillating file for generator power settings 1 to 5 (minimum to half power). Measurements were repeated ten times. The fundamental vibration frequency for both files was 27.50 kHz. Scans of each file showed the positions of nodes/anti-nodes along the file length. The #15 file demonstrated no significant variation in its mean maximum displacement amplitude with increasing generator power, except at power setting 5, where a decrease in displacement amplitude was observed. The #35 file showed a general increase in mean maximum displacement amplitude with increasing power setting, except at power setting 4 where a 65% decrease in displacement amplitude occurred. In conclusion, scanning laser vibrometry is an effective method for assessing endosonic file vibration characteristics. The SLV was able to demonstrate that (unloaded) file vibration displacement amplitude does not increase linearly with increasing generator power. Further work is being performed on a greater variety of files and generators. Vibration characteristics of files under various loads and varying degrees of constraint should also be investigated.